In recent years, wireless communications have become increasingly important in a number of vehicle control systems. Remote vehicle entry transmitters/receivers, for example, are used for locking and unlocking a vehicle door, unlatching a trunk latch, starting the vehicle, or activating or deactivating an alarm system equipped on the vehicle. This remote entry device is commonly referred to as a remote keyless entry (RKE) fob. The RKE fob is typically a small rectangular or oval plastic housing with a plurality of depressible buttons for activating each one of the wireless operations. The RKE fob is carried with the operator of a vehicle and can wirelessly perform these functions when within a predetermined reception range of the vehicle. The RKE fob communicates with an electronic control module within the vehicle via a radio frequency (RF) communication signal.
Even more recently, complex embedded electronic systems have become common to provide access and start functions and to provide wide ranging functions to improve driver safety and convenience. These systems include Passive Entry and Passive Start (PEPS) systems which include a remote receiver and transmitter (or transceiver) and an electronic control module disposed within the vehicle. In a PEPS system, a remote transceiver is carried with the user in a portable communication device such as a key fob or a card. The portable communication device when successfully challenged transmits an RF signal to a PEPS module within the vehicle which starts the authentication process to validate the user. The PEPS module in turn sends status information on a system vehicle bus to other vehicle control modules which perform a variety of tasks such as door lock/unlock, enabling engine start, or activating external/internal lighting.
In addition to keyless and passive entry systems, “gesture recognition” has become important for accessing vehicles. Capacitive sensors include a sensor electrode or multiple electrodes which can detect an object in a “detection area” space in front of the sensor electrode(s). In one type of system, for example, a control and evaluation circuit is coupled to the sensor electrode and detects a change in the capacitance of the sensor electrode with respect to a reference potential. These sensors can be coupled to a non-metallic portion of the vehicle, such as the region of a lower sill area, lower fender or bumper, and are typically used to operate (open/close) a door of a motor vehicle, a trunk, or a tailgate by detecting the approach of a body part. For example, a pivoting movement of a leg/foot under the bumper and forward under it can serve as a command to open or close the trunk or tailgate to a control device in the motor vehicle. The “gesture sensor” can, in some applications, be combined and monitored in conjunction with the proximity of a keyfob or PEPS device to assure that the person providing the “gesture” also has the right to access the vehicle.